Combination weighers are roughly classified into an automatic combination weigher, a semiautomatic combination weigher and a hand-operated (manual) combination weigher, depending on a difference in a feeding method and a discharge method of objects with respect to a weighing unit. In the hand-operated combination weigher, feeding and discharging of the objects are performed manually by an operator. In the semiautomatic combination weigher, feeding of the objects is performed manually by the operator, while discharging of the objects is performed automatically (see e.g., Patent Literature 1). In the automatic combination weigher, feeding and discharging of the objects are performed automatically (mechanic control) (see e.g., Patent Literature 2).
For objects which are incapable of being fed automatically to a combination weigher or objects which are not suitable for use in the automatic feeding, the hand-operated combination weigher or the semiautomatic combination weigher is used.
In a conventional semiautomatic combination weigher, for example, a plurality of hoppers are aligned, and a single belt conveyor is placed under the plurality of hoppers. When the operator feeds objects to hoppers, the objects are weighed, discharge gates of hoppers selected to make up a combination in which a combination weight falls within a predetermined weight range are opened and closed to discharge the objects, the objects discharged from the hoppers are conveyed in one direction by a belt conveyor, and the objects are discharged to a subsequent-stage apparatus, such as a packaging machine.